1. Field of the Invention
This invention relates to a ship's hull for small vessels and high speeds with static and dynamic buoyancy.
2. Description of the Prior Art
Small, fast ships, in particular motorboats and military vessels, are predominantly designed as dual-screw (or dual propeller) vessels, because with two or four screws, the propeller's tendency toward cavitation is reduced, and hydrodynamic nonuniformity of the drive can be prevented.
The prior art includes the following solutions to prevent cavitation:
1. The production of a uniform slipstream field in the axial, radial and tangential direction;
2. The prevention of a diagonal flow;
3. The choice of a large propeller diameter and/or a high surface ratio; and
4. The distribution of the power to two propellers located one behind the other (contra-rotating propellers).
In addition, the prior art does not include suitably high-powered drive equipment.
Finally, even today, the argument is used that with dualscrew (or dual propeller) vessels, the vessel can still be operated even if one drive engine fails, and that the dual-screw drive allows improved maneuvering characteristics.
In commercial shipping, multi-screw drives have been almost completely abandoned in the last ten to fifteen years, because a single-screw drive reduces the investment cost by approximately 10 percent and the fuel costs by approximately 15 percent. In addition, the control characteristics of the vessel are significantly better during slow-speed travel than with dual-screw vessels, if the latter are equipped with a central rudder.
Examples of prior art which relate to ships or vessels employing propeller propulsion, and the technical concerns relating thereto, are: U.S. Pat. No. 4,383,828, entitled "Power Boat with Extended Propeller Pocket"; U.S. Pat. No. 4,459,116, entitled "Screw Propelled Water Saddle"; U.S. Pat. No. 4,010,707, entitled "Marine Propulsion Unit"; U.S. Pat. No. 4,428,734, entitled "Planing-Hull Type Boats and Power Drives Therein"; U.S. Pat. No. 3,937,173 entitled "Deep-V Tunnel Stern Boat"; U.S. Pat. No. 3,924,557, entitled "Propeller Mechanism for Boats"; U.S. Pat. No. 4,609,360, entitled "Boat Hull with Flow Chamber"; and U.S. Pat. No. 4,300,889, entitled "Shallow Draft Propeller Pocket".
All of the aforementioned prior art documents relating to propeller driven ships or vessels are hereby expressly incorporated by reference, with the same effect as if set forth in their entireties herein.